1. Technical Field
This disclosure relates to optical element driving circuits. In particular, this disclosure is directed to flexible driving circuits which may produce any of multiple different output intensities from a flash tube.
2. Related Art
Visual emergency warning systems, including strobe alarms, have recently incorporated output intensity adjustments. The intensity adjustments allow the warning systems to output light at different intensities, thereby eliminating the need for a manufacturer to produce multiple separate devices each with a fixed output intensity. The ability to adjust the intensity of the light output provides an installer the flexibility to adapt one model of a strobe alarm for many different environments, each of which may call for a different output intensity. To adapt the warning system for any particular environment, an installer configures the strobe alarm (e.g., using a switch or a jumper) at the time of installation to select one of the output intensities that the strobe alarm supports.
Many strobe alarms include basic driving circuits which rely on a step-up transformer to prime a flash tube for illumination and a voltage doubler to start the flash tube. At high candela settings, the high voltages in the driving circuits can cause damaging arcing at and around the flashtube, step-up transformer and the voltage doubler. Therefore, a need exists for an optical element driving circuit that provides the flexibility of different light output intensities and reliable flash tube operation and which also mitigates or eliminates high voltage arcing.